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/*
* Copyright (c) 2018-2020, Andreas Kling <kling@serenityos.org>
*
* SPDX-License-Identifier: BSD-2-Clause
*/
#include <AK/ScopeGuard.h>
#include <AK/String.h>
#include <AK/TemporaryChange.h>
#include <AK/Vector.h>
#include <errno.h>
#include <pwd.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
extern "C" {
static FILE* s_stream = nullptr;
static unsigned s_line_number = 0;
void setpwent()
{
s_line_number = 0;
if (s_stream) {
rewind(s_stream);
} else {
s_stream = fopen("/etc/passwd", "r");
if (!s_stream) {
perror("open /etc/passwd");
}
}
}
void endpwent()
{
s_line_number = 0;
if (s_stream) {
fclose(s_stream);
s_stream = nullptr;
}
}
struct passwd* getpwuid(uid_t uid)
{
setpwent();
ScopeGuard guard = [] { endpwent(); };
while (auto* pw = getpwent()) {
if (pw->pw_uid == uid)
return pw;
}
return nullptr;
}
struct passwd* getpwnam(char const* name)
{
setpwent();
ScopeGuard guard = [] { endpwent(); };
while (auto* pw = getpwent()) {
if (!strcmp(pw->pw_name, name))
return pw;
}
return nullptr;
}
static bool parse_pwddb_entry(char* raw_line, struct passwd& passwd_entry)
{
size_t line_length = strlen(raw_line);
for (size_t i = 0; i < line_length; ++i) {
auto& ch = raw_line[i];
if (ch == '\r' || ch == '\n')
line_length = i;
if (ch == ':' || ch == '\r' || ch == '\n')
ch = '\0';
}
auto line = StringView { raw_line, line_length };
auto parts = line.split_view('\0', SplitBehavior::KeepEmpty);
if (parts.size() != 7) {
dbgln("getpwent(): Malformed entry on line {}", s_line_number);
return false;
}
auto& name = parts[0];
auto& passwd = parts[1];
auto& uid_string = parts[2];
auto& gid_string = parts[3];
auto& gecos = parts[4];
auto& dir = parts[5];
auto& shell = parts[6];
auto uid = uid_string.to_uint();
if (!uid.has_value()) {
dbgln("getpwent(): Malformed UID on line {}", s_line_number);
return false;
}
auto gid = gid_string.to_uint();
if (!gid.has_value()) {
dbgln("getpwent(): Malformed GID on line {}", s_line_number);
return false;
}
passwd_entry.pw_name = const_cast<char*>(name.characters_without_null_termination());
passwd_entry.pw_passwd = const_cast<char*>(passwd.characters_without_null_termination());
passwd_entry.pw_uid = uid.value();
passwd_entry.pw_gid = gid.value();
passwd_entry.pw_gecos = const_cast<char*>(gecos.characters_without_null_termination());
passwd_entry.pw_dir = const_cast<char*>(dir.characters_without_null_termination());
passwd_entry.pw_shell = const_cast<char*>(shell.characters_without_null_termination());
return true;
}
struct passwd* getpwent()
{
static struct passwd passwd_entry;
static char buffer[1024];
struct passwd* result;
if (getpwent_r(&passwd_entry, buffer, sizeof(buffer), &result) < 0)
return nullptr;
return result;
}
int getpwent_r(struct passwd* passwd_buf, char* buffer, size_t buffer_size, struct passwd** passwd_entry_ptr)
{
if (!s_stream)
setpwent();
while (true) {
if (!s_stream || feof(s_stream)) {
*passwd_entry_ptr = nullptr;
return ENOENT;
}
if (ferror(s_stream)) {
*passwd_entry_ptr = nullptr;
return ferror(s_stream);
}
++s_line_number;
char* s = fgets(buffer, buffer_size, s_stream);
if ((!s || !s[0]) && feof(s_stream)) {
*passwd_entry_ptr = nullptr;
return ENOENT;
}
if (strlen(s) == buffer_size - 1) {
*passwd_entry_ptr = nullptr;
return ERANGE;
}
if (parse_pwddb_entry(buffer, *passwd_buf)) {
*passwd_entry_ptr = passwd_buf;
return 0;
}
}
}
// https://pubs.opengroup.org/onlinepubs/9699919799/functions/getpwnam.html
int getpwnam_r(char const* name, struct passwd* pwd, char* buffer, size_t bufsize, struct passwd** result)
{
setpwent();
for (;;) {
if (auto rc = getpwent_r(pwd, buffer, bufsize, result); rc != 0)
return rc;
if (strcmp(pwd->pw_name, name) == 0)
return 0;
}
}
// https://pubs.opengroup.org/onlinepubs/9699919799/functions/getpwuid.html
int getpwuid_r(uid_t uid, struct passwd* pwd, char* buffer, size_t bufsize, struct passwd** result)
{
setpwent();
for (;;) {
if (auto rc = getpwent_r(pwd, buffer, bufsize, result); rc != 0)
return rc;
if (pwd->pw_uid == uid)
return 0;
}
}
int putpwent(const struct passwd* p, FILE* stream)
{
if (!p || !stream || !p->pw_passwd || !p->pw_name || !p->pw_dir || !p->pw_gecos || !p->pw_shell) {
errno = EINVAL;
return -1;
}
auto is_valid_field = [](char const* str) {
return str && !strpbrk(str, ":\n");
};
if (!is_valid_field(p->pw_name) || !is_valid_field(p->pw_dir) || !is_valid_field(p->pw_gecos) || !is_valid_field(p->pw_shell)) {
errno = EINVAL;
return -1;
}
int nwritten = fprintf(stream, "%s:%s:%u:%u:%s,,,:%s:%s\n", p->pw_name, p->pw_passwd, p->pw_uid, p->pw_gid, p->pw_gecos, p->pw_dir, p->pw_shell);
if (!nwritten || nwritten < 0) {
errno = ferror(stream);
return -1;
}
return 0;
}
}
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